diff --git a/.gitignore b/.gitignore
index 722d5e7..af96791 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
 .vscode
+build
diff --git a/Makefile b/Makefile
index 9bca313..fc575b4 100644
--- a/Makefile
+++ b/Makefile
@@ -1,8 +1,31 @@
-BOARD = --board adafruit:samd:adafruit_trellis_m4
+FQBN = adafruit:samd:adafruit_trellis_m4
 
-verify: uilleann.ino
-	arduino --verify $(BOARD) $<
+default: build/uilleann.ino.uf2
+
+# uf2conv.py is covered by an MIT license.
+build/uf2conv.py:
+	mkdir -p build
+	curl -L https://raw.githubusercontent.com/microsoft/uf2/master/utils/uf2conv.py > $@
+	chmod +x $@
+
+%.uf2: %.bin build/uf2conv.py
+	build/uf2conv.py -b 0x4000 -c -o $@ $<
+
+build/%.bin: % *.cpp *.h
+	arduino-builder \
+		-build-cache ~/.cache/arduino \
+		-build-path build \
+		-core-api-version 10813 \
+		-fqbn $(FQBN) \
+		-hardware ~/.arduino15/packages \
+		-tools /app/Arduino/tools-builder \
+		-tools ~/.arduino15/packages \
+		-hardware /app/Arduino/hardware \
+		-hardware ~/.arduino15/packages \
+		-built-in-libraries /app/Arduino/libraries \
+		-libraries ~/Arduino/libraries \
+		-compile \
+		$<
 	
-install: uilleann.ino
-	arduino --upload $(BOARD) $<
-
+upload: uilleann.ino
+	arduino --upload --board $(FQBN) $<